Image Forming Apparatus Trailing End Voltage Control
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Solution Overview
Problem
In electrophotographic image forming apparatuses, the trailing end of recording materials often experiences contamination due to the reduction of transfer voltage, which weakens the retaining force of contamination toner on the transfer roller, leading to paper end contamination and reduced photosensitive member lifetime.
Innovation Solution
An image forming apparatus with a controller that adjusts the trailing end voltage of the transfer member, changing it to a first voltage lower than the transfer voltage during image transfer and a second voltage of opposite polarity to the toner's charge polarity after the image forming operation is incomplete, to manage contamination and extend the photosensitive member's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the transfer voltage is reduced when the trailing end passes through the transfer nip, then the photosensitive member lifetime is extended, but the retaining force of contamination toner on the transfer roller is weakened causing paper end contamination
Solution Approach 1:
The trailing end voltage control is divided into two distinct segments: a first trailing end voltage applied during normal operation to extend photosensitive member lifetime, and a second trailing end voltage of opposite polarity applied after incomplete image forming operations to prevent paper end contamination. This segmentation allows optimization for different operational conditions.
Solution Approach 2:
The transfer roller voltage is made dynamic by switching between different voltage states based on operational conditions. The controller adjusts the voltage from the first trailing end voltage to the second trailing end voltage of opposite polarity when detecting incomplete image forming operations, allowing the system to adapt to varying operational requirements.
2Object-affected harmful factors
If the transfer voltage is made lower during trailing end passage, then electric discharge current is reduced suppressing abrasion, but contamination toner is transferred onto the trailing end of recording material
Solution Approach 1:
The second trailing end voltage of opposite polarity is applied in advance after incomplete image forming operations to counteract the potential contamination before it occurs. This preliminary anti-action prevents the transfer of contamination toner onto the recording material trailing end by creating an electrostatic barrier.
Solution Approach 2:
Instead of continuously applying a low voltage to reduce abrasion (which causes contamination), the system inverts the approach by applying a voltage of opposite polarity in specific conditions. This inversion creates an electrostatic field that repels contamination toner while the first trailing end voltage continues to protect against abrasion during normal operation.
3Object-generated harmful factors
If the voltage is changed to opposite polarity to prevent contamination, then paper end contamination is suppressed, but the system complexity increases due to dual voltage control
Solution Approach 1:
The transfer roller voltage control system serves multiple functions: it extends photosensitive member lifetime through the first trailing end voltage, prevents paper end contamination through the second trailing end voltage of opposite polarity, and manages contamination toner. This multi-functionality justifies the increased control complexity by consolidating multiple protection mechanisms into a single voltage control system.
Solution Approach 2:
The controller uses feedback from the image forming operation status to determine when to switch between voltage modes. When incomplete image forming operations are detected, the system automatically transitions to the second trailing end voltage, creating a closed-loop control system that adapts to operational conditions without requiring complex manual intervention.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively suppresses paper end contamination and extends the photosensitive member's lifetime by optimizing voltage control during the trailing end passage and post-operation states.
Implementation Method 1
a transfer voltage of an opposite polarity to a normal charge polarity of the toner is applied to the transfer roller, so that charges are imparted to the recording material and thus the toner image on the photosensitive member is transferred onto the recording material
Implementation Method 2
When a current by electric discharge flows through between the photosensitive member and the transfer roller under application of the transfer voltage to the transfer roller, the surface of the photosensitive member is abraded
Data Source
AI summary
An image forming apparatus includes a rotatable photosensitive member, a charging member, a developing member, a transfer member, a voltage applying portion, and a controller. The controller is capable of changing a trailing end voltage to a first trailing end voltage lower than a transfer voltage applied to the transfer member by the voltage applying portion when a toner image is transferred from the photosensitive member to a recording material and to a second trailing end voltage higher than the first trailing end voltage. In an image forming operation after rotation of the photosensitive member is stopped in a state in which the image forming operation is not completed, the controller carries out control so that the second trailing end voltage is applied when a trailing end of the recording material with respect to a feeding direction passes through a transfer portion.